Severe acute respiratory syndrome (SARS) is a newly recognized illness associated with substantial morbidity and mortality. Patients develop fever followed by rapidly progressive and even fatal respiratory disease. SARS is associated with infection with a novel coronavirus. The evaluation of the inflammatory responses evoked by SARS may yield information regarding its pathogenesis and help with patient management. We aim to study disease pathogenesis and natural history, by studying samples and data that are collected by outside physicians or physicians at the Clinical center and sent for evaluation of the inflammatory response.